Vapor deposition surface treatment is divided into physical vapor deposition, chemical vapor deposition and physical and chemical mixed vapor deposition, or divided into evaporation, plasma multi-arc sputtering, magnetron sputtering and reactive sputtering according to the principle. Vapor deposition is widely used in the manufacturing industry of automotive parts. Automotive hubs using magnetron sputtering as surface decoration have been applied and promoted in the after-market. The characteristic of vapor deposition is to achieve a metallic mirror gloss decoration effect on the surface of a part. By combining with conventional coating, not only the part is elegant, but also the coating performance can meet the automotive factory standards.
Reactive magnetron sputtering refers to a method in which a reactive gas is introduced to a vacuum chamber during magnetron sputtering to chemically react with the sputtered technical ions to produce a new compound deposited on the surface of a substrate, and the percentage of the compound deposited on the surface of the workpiece is controlled according to the concentration of the introduced reactive gas to form a related alloy coating film. This method can achieve a new black and shiny metallic appearance effect of a glossy mirror, and is environment-friendly and low in cost.
A non-magnetic metal or alloy material is selected as the target according to the requirements of corrosion resistance, weather resistance, decoration and the like of a surface coating of a hub. If the rough surface of the cast aluminum alloy hub is directly coated, a shiny coating cannot be formed. Therefore, a coating must be sprayed onto the hub to form a mirror surface, and then the shiny surface is coated. In order to prolong the long-lasting gloss and long service life of the metal coating film, a transparent powder coating is sprayed onto the coating film to obtain an attractive and durable coating. At the same time, the coating material is required to be well bonded with the upper and lower coatings and also have strong corrosion resistance.
There are many methods using magnetron coating: I, a black clear lacquer is sprayed onto the bright white metal coating film to achieve a bright black chromium appearance; and II, black high gloss resin is sprayed onto the metal coating film to reduce the thickness of the coating film, so that the coating film is translucent, transmits the underlying black and is black and shiny. The above two methods have respective advantages and disadvantages: in the first method, the black clear lacquer easily produces color aberration, the black clear lacquer is different in thickness and color, and the black transparent coating generally has a thickness of 10-30 microns, is poor in protection on the coating film and cannot achieve long-term use standards; and in the second method, the translucent coating film cannot completely cover the underlying resin, and long-term exposure and ultraviolet aging lead to interlayer adhesion failure.